Method and apparatus for digital communications with multiparameter light fixtures

ABSTRACT

A typical light fixture is an integral unit that has a lamp assembly and a communications node to control the lamp assembly. Lighting systems contain many such light fixtures. One type of lighting system has at least two communications systems that interconnect the light fixtures. A digital controller is connected to one of the communications systems, at least one of the light fixtures of that communications system is a designated gateway for sending control signals to the other communications system. Another type of lighting system has two digital controllers connected to respective communications systems. Each of the communications systems interconnects many light fixtures, at least one of which has two communications nodes respectively connected to the communications systems. A third type of lighting system mixes combines the first and second types.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a division of nonprovisional application Ser.No. 09/394,300, filed Sep. 10, 1999, allowed, now U.S. Pat. No.6,331,756, which hereby is incorporated herein by reference in itsentirety, as though fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to digital control of lighting devices,and more particularly to digital control of large lighting systems,including systems having multi-parameter light fixtures, with multiplecommunications systems.

2. Description of Related Art

Multi-parameter light fixtures, which include light fixtures havingindividually remotely adjustable beam size, color, shape, angle, andother light characteristics, are widely used in the lighting industrybecause they facilitate significant reductions in overall lightingsystem size and permit dynamic changes to the final lighting effect.

Applications and events in which multi-parameter light fixtures are usedto great advantage include showrooms, television lighting, stagelighting, architectural lighting, live concerts, and theme parks.

In practice, the multi-parameter light fixtures of a system aretypically controlled by a central controller. Prior to the advent ofrelatively small commercial digital computers, remote control of lightfixtures from a central controller was done with either a high voltageor low voltage current; see, e.g., U.S. Pat. No. 3,706,914, issued Dec.19, 1972 to Van Buren, and U.S. Pat. No. 3,898,643, issued Aug. 5, 1975to Ettlinger. With the widespread use of computers, digital serialcommunications was widely adopted as a way to achieve remote control;see, e.g., U.S. Pat. No. 4,095,139, issued Jun. 13, 1978 to Symonds etal., and U.S. Pat. No. 4,697,227, issued Sep. 29, 1987 to Callahan.

Digital communications between the central controller and themulti-parameter light fixtures typically is by wire. In 1986, the UnitedStates Institute of Theatre Technology (“USITT”) developed a digitalcommunications system protocol for multi-parameter light fixtures knownas DMX512. While the DMX512 protocol has been updated several timessince its adoption, the basic communications protocol remains the same.Basically, the DMX512 protocol consists of a stream of data which iscommunicated one-way from the control device to the light fixture usingan Electronics Industry Association (“EJA”) standard for multipointcommunications know as RS-485. FIG. 1 shows an illustrative system basedon the USITT DMX512 protocol. Power mains 12 provide AC power to acentral controller 10 and light fixtures 20, 22, 24, 26, 32, 34 and 36over standard building electrical wiring 14. A communications cable 16is run from the central controller 10 to the first multi-parameter lightfixture 20, and additional communication cable segments 21, 23, 25, 31,33 and 35 sequentially connect the light fixtures 22, 24, 26, 32, 34 and36. While only seven multi-parameter light fixtures are shown in FIG. 1for clarity, typically multi-parameter lighting systems may have thirtyor more such light fixtures. Communication is in a single direction, asshown by arrows adjacent the communications cable 16 and cable segments21, 23, 25, 31, 33 and 35. From time to time, light fixtures must beplaced in locations which are hard to reach or otherwise presentdifficulties during installation and cabling. A hard to reach ordifficult area 30 containing light fixtures 32, 34 and 36 is included inFIG. 1.

An illustrative light fixture 100 suitable for use in themulti-parameter lighting system of FIG. 1 is shown in greater detail inFIGS. 2 and 3. The front view of FIG. 2 shows a light housing 110 whichis rotatably attached to a yoke 108. The yoke 108 is in turn rotatablyattached to an electronics module 104, which contains a power supply andcommunications and control electronic circuits. A panel area 106 on theelectronics module 104 contains a display and various buttons formanually setting the operating address of the light fixture 100. Theside view of FIG. 3 shows that the electronics module 104 also includesa pair of digital communications terminals, one of which is a digitalinput terminal 112 designated DIGITAL LINE IN and the other of which isa digital output terminal 114 designated DIGITAL LINE OUT. Internally,the input terminal 112 typically is looped through to the outputterminal 114. Respective communications cables plug into the terminals112 and 114. A line cord 102 for connecting the multi-parameter lightfixture 100 to the power line extends from the electronics module 104.Illustrative multi-parameter light devices are described in the productbrochure entitled The High End Systems Product Line 1996 and areavailable from High End Systems, Inc. of Austin, Tex.

To maintain reliability throughout the multi-parameter lighting system,the communications cables typically are dedicated metallic or fiberoptic cables. One reason is the central controller for themulti-parameter light fixtures of a system may be a considerabledistance from the light fixtures. For example, central controllers maybe located over one hundred meters from the light fixtures they controlin such places as large arenas, theaters, and auditoriums. Lengthy cableruns are also found in commercial buildings in which light fixtures areused for architectural lighting, since the communications cables mustpass from floor to floor or between widely separated rooms on the samefloor. Moreover, a typical large lighting system contains over thirtylight fixtures and a corresponding number of communications cablesbetween the light fixtures, and requires significant labor to connectsecurely each of the light fixtures and the central controller to thepower mains and their respective communications cables. Installation ofmulti-parameter lighting systems tend to be quite costly, taking intoconsideration the individual costs of the cables, the associatedconnectors, and the labor involved in installing them.

During the transition from analogue control to digital control, somemulti-parameter light fixtures were constructed with both a digital andan analog means of communication. An example of such a device is theTrackSpot® automated luminaire, which is described in the productbrochure entitled The High End Systems Product Line 1996 and isavailable from High End Systems Inc. of Austin, Tex. The TrackSpotsystem has a wide variety of control options, including digital andanalog. The analog communication is designed as an input, and the deviceis manually selectable between the digital and analog input schemes. Theanalog communication to the device controls the device that it isconnected to, whereas the digital communications “loops through” fromlight to light with an addressable signal scheme for controllingmultiple addressed light fixtures.

The TrackSpot fixture is physically switched on the fixture to assumeeither a master or a slave position. With the fixture set to the masterposition, an analog signal at the analog input to the fixture causes themaster to execute a particular one of numerous memory resident programsbased on the analog value it receives. The master also sends a digitalsignal to the other fixtures that are set up as “slaves” to cause themto act on their respective memory resident programs.

Despite advances in the control of large lighting systems, a need existsfor improving the digital control of large systems that includemulti-parameter light fixtures.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention as realized inparticular embodiments is to reduce the cost of installing anddismantling complex lighting systems generally, and multi-parameterlighting systems particularly.

Another object of the present invention as realized in particularembodiments is to provided multiple levels of communications forcontrolling complex lighting systems generally, and multi-parameterlighting systems particularly.

Yet another object of the present invention as realized in particularembodiments is to extend the capabilities of complex lighting systemsgenerally, and multi-parameter lighting systems particularly, whilemaintaining essential core reliability.

These and other objects are achieved in the various embodiments of thepresent invention. For example, one embodiment of the present inventionis a lighting system comprising a first digital communications system, afirst controller connected to the first digital communications system, asecond digital communications system, a first plurality ofmulti-parameter light fixtures interconnected by the first digitalcommunications system, and a second plurality of multi-parameter lightfixtures interconnected by the second digital communications system. Thefirst and second plurality of light fixtures includes at least onegateway-capable light fixture that is interconnected in both the firstand second digital communications systems.

Another embodiment of the invention is a lighting system comprising afirst digital communications system, a first controller connected to thefirst digital communications system, a second digital communicationssystem, a second controller connected to the second digitalcommunications system, and a plurality of multi-parameter light fixturesinterconnected by the first digital communications system and alsointerconnected by the second digital communications system.

A further embodiment of the invention is a multi-parameter light fixturecomprising a lamp assembly, a first digital communications node having afirst control output coupled to the lamp assembly and a firstcommunications port, a second digital communications node having asecond communications port, and a gateway circuit coupled between thefirst digital communications node and the second digital communicationsnode. In further embodiments, at least one of the first and secondcommunications nodes supports bi-directional digital communications, andthe second digital communications node further comprises a secondcontrol output coupled to the lamp assembly.

Another embodiment of the invention is a method of controlling alighting system, comprising controlling a first plurality ofmulti-parameter light fixtures over a first communications system,controlling a second plurality of multi-parameter light fixtures over asecond communications system and controlling the second plurality ofmulti-parameter light fixtures over the first communications systemthrough one of the first plurality of multi-parameter light fixturesacting as a gateway.

Another embodiment of the invention is a method of controlling amulti-parameter light fixture with a first command type, comprisingassigning priority to a first communications system, the multi-parameterlight fixture being controllable by the first communications and by asecond communications system; responding to commands of the firstcommand type on the first communications system; and ignoring commandsof the first command type on the second communications system. In afurther embodiment, the multi-parameter light fixture is controllablewith a second command type and further comprises responding to commandsof the second command type on the second communications system.

A further embodiment of the invention is a method of controlling amulti-parameter light fixture with a first command type, comprisingassigning priority to a first communications system, the multi-parameterlight fixture being controllable by the first communications and by asecond communications system; detecting whether the first communicationssystem is in an active or inactive state; ignoring commands of the firstcommand type on the second communications system when the active stateis detected in the detecting step; and responding to commands of thefirst command type on the second communications system when the inactivestate is detected in the detecting step.

Another embodiment of the invention is a method of controlling alighting system, comprising controlling a first plurality ofmulti-parameter light fixtures over a first communications system;controlling a second plurality of multi-parameter light fixtures over asecond communications system, at least two of the multi-parameter lightfixtures in the first plurality of multi-parameter light fixtures beinggateways from the first communications system to the secondcommunications system; and establishing one of the gateways as an activegateway from the first communications system to the secondcommunications system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a prior art lighting system.

FIG. 2 is a plan front view of a multi-parameter light fixture.

FIG. 3 is a plan side view of the multi-parameter light fixture of FIG.2.

FIG. 4 is a block schematic diagram of a lighting system havingcommunications systems in accordance with the present invention.

FIG. 5 is a block schematic diagram of another lighting system havingcommunications systems in accordance with the present invention.

FIG. 6 is a schematic diagram of lighting system having a cablecommunications system and a power line communications system, inaccordance with the present invention.

FIG. 7 is a schematic diagram of lighting system having twocommunications systems with respective controllers, in accordance withthe present invention.

FIGS. 8, 9 and 10 are block schematic diagrams showing variousarrangements of communications systems interfaces, in accordance withthe present invention.

FIGS. 11, 12, 13 and 14 are block schematic diagrams showing variousterminal arrangements.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Lighting systems that include multi-parameter light fixtures andmultiple digital communications systems are generally characterized byFIG. 4, by FIG. 5, or by a combination of FIGS. 4 and 5. These systemsinclude digital controllers (controller 302 in FIG. 4 and controllers402 and 406 in FIG. 5) which issue digital commands recognizable bynodes in the system that control the light effects, and whichcommunicated using any suitable protocol such as a one waycommunications protocol, the DMX512 protocol for example, or abi-directional communications protocol. A multi-parameter light fixtureis an integral unit that includes a lamp assembly and one communicationsnode, or an integral unit that includes a lamp assembly and two or morecommunications nodes, or an integral unit that includes a lamp assembly,two or more communications nodes, and a gateway circuit or circuitsbetween the communications nodes. The communications nodes of amulti-parameter light fixture reside in the fixture and are part of it.A lamp assembly for a multi-parameter light fixture includes a lamp,typically but not necessarily a high intensity lamp, and one or moreother components such as, but is not limited to, the following: motors,filters, lenses, prisms, gobo wheels, shutters, iris diaphragms, andcircuits for achieving optical effects such as frost and diffusion, zoomand focus, pan and tilt, iris, independent or interactive three coloreffects, and rotating and static gobo patterns.

Generally, a gateway is any electronic circuit that permits signals topass between communications systems either unidirectionally orbi-directionally. Gateways may or may not perform protocol conversion,depending on whether the communications systems operate on differentcommunications protocols. Suitable gateway circuits and protocolconverters are well known in the electronic circuit arts.

The lighting system of FIG. 4 illustratively has three lightingcommunications systems 310, 320 and 330. A digital controller 302 isconnected to the communications system 310 and light fixtures 312, 314and 316 are interconnected by the communications systems 310 in anysuitable way. Light fixtures 314 and 322 are interconnected by thecommunications systems 320 in any suitable way. Light fixtures 316 and332 are interconnected by the communications systems 330 in any suitableway. Some light fixtures include gateways between two or more of thecommunications systems, through which at least some of the controlsignals from the communications system 310 are furnished to thecommunications systems 320 and 330. For example, light fixture 314includes a gateway circuit (not shown) between the communicationssystems 310 and 320, and is controllable from the communications system310. Similarly, light fixture 316 includes a gateway circuit (not shown)between the communications systems 310 and 330, and is controllable fromthe communications system 310. While FIG. 4 shows only one gatewayinstalled between different communications systems, more than onegateway may be installed between different communications systems ifdesired. While FIG. 4 shows three lighting communications systems 310,320 and 330, the use of only two or three or more communications systemsis contemplated.

In the lighting system of FIG. 5, the digital controller 402 isconnected to lighting communications system 404 and light fixtures 410are interconnected by the communications systems 404 in any suitableway. The digital controller 406 is connected to lighting communicationssystem 408 and light fixtures 410 and 412 are interconnected by thecommunications systems 408 in any suitable way. Some light fixtures suchas light fixtures 410 are controllable from both of the lightingcommunications systems 404 and 408. If desired, any of the lightfixtures 410 may be provided with gateways to enable communicationsbetween communications systems 404 and 408. While FIG. 5 shows twolighting communications systems 404 and 408, the use of two or morecommunications systems is contemplated.

Preferably, one of the lighting communications systems and itsinterconnection to a digital controller has high reliability, which isachieved by using reliable and securely installed electrical or opticalphysical cables and connectors. For example, in FIG. 4 the digitalcontroller 302 and the lighting communications system 310 use highreliability digital communications, and in FIG. 5 the digital controller402 and the lighting communications system 404 use high reliabilitydigital communications. Other lighting communications systems in thelighting system may be of low reliability or a mix of high and lowreliability, as desired, and may use various communications techniquesdepending on project budget and site characteristics. Power linecommunications and wireless communications such as radio frequency andinfrared are particularly useful where physical access is difficult orwhen installation time is limited.

Suitable wired communications systems include parallel or serial bus, inseries wiring, star ring network, FDDI ring network, token ring network,and so forth. Suitable wired communications protocol include the DMX512protocol for unidirectional communications over conductors, and theCEBus (Consumer Electronics Bus) Standard EIA-600 for communicationsover a power line. If bi-directional communications is desired using theDMX512 protocol, additional conductors and suitable interfaceelectronics for full duplex are used, since the DMX512 protocol does notsupport bi-directional communications over the same conductors. Suitablewireless communications systems include radio frequency and infrared.Suitable wireless communications protocols include the previouslymentioned CEBus Standard, which also applies to RF and infraredcommunications.

Having two or more communications systems available in a multi-parameterlighting system enables the system designer to optimize individualcommunications systems as required. A multi-parameter light fixturecommunicating over a first lighting communications system may act as agateway to supply commands to multi-parameter light fixturescommunicating over a second lighting communications system. Although thesecond communications system may be of the same type as the first,preferably the second communications system is of a different type.Where the first communications system is a cable based system, forexample, the second system may be a wired or wireless communicationssystem and may have greater speed or another performance advantage orease of installation or other capability that the first system does nothave. For example, a second communications system may conform to theANSI/EIA-600 protocol used for the CEBus. Light fixtures conforming tothis protocol would be compatible with and could be controlled fromother devices conforming to the ANSI/EIA-600 protocol if desired.

The use of a multi-parameter light fixture acting as a gateway from onecommunications system to another different communications system may bebetter understood from the following example. A multi-parameter lightfixture resident on a first communications system receives andpreferably performs an operation in accordance with commands from aparticular command set. If the multi-parameter light fixture is also agateway, it retransmits those commands on one or more additionalcommunications systems on which it is also resident. The othermulti-parameter light fixtures on the additional communications systemsparticipate in the operation, if so commanded. Where different protocolsare used for the different communications systems, the gatewaymulti-parameter light fixture includes a communications converter. Thecontainment of a communications converter at the gateway multi-parameterlight fixture adds negligible additional complexity to many of thecommercially available multi-parameter light fixtures that containmicroprocessor systems, since the programs operating the microprocessorsare easily modified to forward the commands to the appropriate terminalsof the light fixtures and to perform any needed conversion from onecommunications system to another at any desired location.

A gateway may function in any one of a number of ways with respect tothe light fixtures linked to it. One simple and flexible technique isfor the gateway in a multi-parameter lighting fixture to pass allsignals received on one of its connected lighting communications systemson to the other one or more of its connected lighting communicationssystems, with or without protocol conversion as necessary. If thecommand is addressed to the gateway multi-parameter lighting fixture,the fixture responds to the command; otherwise, the command is ignored.It will be appreciated that other gateway techniques may be used, ifdesired. As a further example, the command set may include mode commandsthat switch the addressed gateway multi-parameter light fixture into adesired mode, such as a pass through mode. These techniques,permutations of these techniques, and other suitable techniques asdesired may be used to implement the gateway.

A multi-parameter light fixture on a first communications system actingas a gateway to a second communications system may also be designed torespond to commands on the second communications system originatingfrom, for example, a second controller; see FIG. 5. A multi-parameterlight fixture may also be designed to act as a gateway in eitherdirection, that is as a gateway from a first communications system to asecond communications system as well as a gateway from the secondcommunications system to the first communications system.

In a lighting system such as shown in FIG. 4 having two or morecommunications systems, two or more gateways may be installed betweendifferent communications systems. The selection of which gateway to makeactive is accomplished by any suitable technique. Simple techniquesinvolve a human operator physically setting a switch on one of thegateway multi-parameter light fixtures to activate its gateway function,or issuing a command from the digital controller to select a particularone of the gateway multi-parameter light fixtures and activate itsgateway function. A more complicated but preferable technique is theintelligent arbitration of the nodes in the installation.

In intelligent arbitration, light fixtures connected into both a firstlighting communications system and a second lighting communicationssystem automatically decide amongst themselves which is to act as agateway to the light fixtures receiving communications only from thesecond communications system. Methods of intelligent arbitration arewell known and may be used amongst multi-parameter light fixtures todecide which light fixture receiving communications from the first andsecond communications system should act as a gateway. Only one of thelight fixtures should act as a gateway to transmit command sets from thefirst to the second communications system to avoid collisions.Multi-parameter light fixtures used in an installation are provided withunique operating addresses so that each light may receive and decode itsindividual commands. One way to provide this operating address is forinstallation personnel to manually set the address at the light fixtureusing switches incorporated into the light fixture. In addition,multi-parameter light fixtures typically contain a unique manufacturingaddress, which is different for each light fixture and is used byservice personnel to address the light in a group during the loading ofnew operating software. Other well-known address assignment techniquesmay be used if desired.

In a lighting system such as shown in FIG. 5 having two or morecommunications systems with respective controllers, multi-parameterlight fixtures may be connected to multiple communications systems,either of which may affect light fixture parameters and operations suchas homing and enabling or disabling operational modes. In this event,the multi-parameter light fixtures connected to multiple communicationssystems select which one of the communications systems to respond tousing any suitable priority system. For example, automatic selection bythe priority system may be predisposed by programming at the factory ormay be selected at the multi-parameter light fixture itself by manualentry at the keypad, in a manner well known in the art. The prioritysystem allows the multi-parameter light fixture to select whichcommunications system may provide certain operating commands if thecommands are duplicated by multiple systems. For example, themulti-parameter light fixtures connected to multiple communicationssystems should respond to operating commands such as “lamp on,” “colorchange,” “pattern change,” “position,” “shutter,” “dimmer,” “imagerotate,” and so forth only if from the priority system (when multiplecommunications systems are active), and should ignore similar or evenidentical commands present on another active communications system. Somecommands that may be carried on the second communications system may notconflict with commands on the first communications systems, and theseshould be recognized and executed by the multi-parameter light fixturesconnected to multiple communications systems. For instance, requests forservice information presented over the second communications systemshould be responded to regardless of whether the first or secondcommunications system is the priority system.

In the event that only one communications system of the lighting systemis active, such as, for example, during light system installation orwhen one of the communications systems fails, the light fixtures in thelighting system should respond to the active communications system. Forexample, in a lighting system having two communications systems and twocontrollers, a first communications system connected to a firstcontroller may be provided because light fixtures on the firstcommunications system have features that benefit from the speed orbi-directional capability or other capabilities of the firstcommunications system, while the second communications system connectedto a second controller may be provided because light fixtures on thesecond communications system lack some of the features of the lightfixtures on the first communications system and the second controllerhandles the transmission of the limited number of parameters to thelight fixtures in the second communications system. The light fixtureson the first communications system may be interconnected in the secondcommunications system, especially if the second controller provides acapability such as requests for service information that the firstcontroller does not provide. When both communications systems areactive, the light fixtures operate using the shared resources andrespond based on priority. When only one communications system isactive, the light fixtures in the lighting system preferably use theactive communications system to the full extents of its capabilities.This is done at the multi-parameter light fixture by recognizing thatonly one communications system is active and automatically switching itsoperation to take fullest advantage of the active communications system.

The absence of commands on a communications system may be detected in avariety of ways. For example, if the communications system protocol isDMX, which operates using a continuous stream of data, then absence ofany data at the communications port signifies that no connection isavailable or no data is available to this communications port. If theprotocol is not DMX but instead a protocol that provides for updates tobe sent only as needed, one illustrative technique for detecting acommunications failure would be to have the protocol specify a minimumnumber of periodic updates to be given during a specified period. If atleast the minimum number of updates are received within the “expectedtime frame,” then communications at the communications port isconsidered active.

FIG. 6 shows a multi-parameter lighting system 500 that uses a cablecommunications system and a power line communications systems actingtogether to control multi-parameter light devices. When using a powerline or radio frequency communications system, multi-parameter lightfixtures are easy to install since dedicated communications cables neednot be run. This is an advantage for shows that have to be constantlyset up and dismantled. A considerable cost savings is realized, sincethe cost associated with the labor needed to run the communicationscables (some in very difficult locations) as well as the cost of thecables themselves are avoided. As shown in FIG. 6, power mains 512provide AC power to a central controller 510 and light fixtures 520,522, 524, 526, 532, 534 and 536 over standard building electrical wiring514. While only seven multi-parameter light fixtures are shown in FIG. 6for clarity, typically multi-parameter lighting systems have thirty ormore such light fixtures. A communications cable 516 is run from thecentral controller 510 to the first multi-parameter light fixture 520,and additional communications cable segments 521, 523 and 525sequentially connect the light fixtures 522, 524 and 526.Illustratively, the DMX512 protocol is used, and the light fixtures 520,522, 524 and 526 have communications cable interfaces of a type wellknown in the art. Light fixtures 532, 534 and 536, which are located ina hard to reach or difficult area 530, are provided with power linecommunications interfaces rather than cable communications interfaces.Illustratively, the CEBus protocol is used. One of the light fixtures520, 522, 524 and 526, illustratively the light fixture 520, is designedas a master and is provided with a power line communications interfacein addition to a communications cable interface. The light fixture 520either initiates a new set of commands to the light fixtures 532, 534and 536 as a function of the command it receives, or alternativelypasses commands from the cable communications system to the power linecommunications system. Depending on the protocol used in the secondcommunications system, the light fixture may or may not reformat thecommands and data between the cable and power line communicationssystems. Advantageously, running communications cables to themulti-parameter lights in the hard to reach or difficult area 530 isunnecessary, and light fixtures are easily installed wherever they areneeded, provided only that a power mains connection can be made.

An example of a dual controller lighting system is shown in FIG. 7.Power mains 612 provide AC power to a controller 610 and light fixtures620, 622, 624, 626, 628, 630 and 632 over standard building electricalwiring 614. While only seven multi-parameter light fixtures are shown inFIG. 7 for clarity, typically multi-parameter lighting systems havethirty or more such light fixtures. A first communications systemincludes communications cable 616, which runs from the controller 610 tothe first multi-parameter light fixture 620, and additionalcommunications cable segments 617, 618 and 619, which sequentiallyconnect the light fixtures 622, 624 and 626. The light fixtures 620,622, 624 and 626 are of any desired multi-parameter type, including, forexample, such advanced types as disclosed in U.S. Pat. No. 5,828,485entitled “Programmable light beam shape altering device usingprogrammable micromirrors” having a variety of advanced features such asvideo projection. The controller 610 is also of an advanced type capableof providing a command set having not only commands typical to standardmulti-parameter light fixtures, but also having commands containingvideo, pixel and other suitable information for the advanced features.An advanced controller 610 supports bi-directional communicationscompliant with a suitable protocol designed to control lights that usecomplex image projection such as that disclosed in U.S. Pat. No.5,828,485, as shown by arrows adjacent communications cable 616, and themulti-parameter light fixtures 620, 622, 624 and 626 have suitablecommunications cable interfaces of a type well known in the art. Powermains 612 also furnish power to another controller, illustratively acomputer 640. A second communications system includes communicationscable 642, which runs from the computer 640 to the first multi-parameterlight fixture 620, and additional communications cable segments 644,645, 646, 647, 648 and 649, which sequentially connect the lightfixtures 622, 624, 626, 628, 630 and 632. The light fixtures 628, 630and 632 are any desired multi-parameter type such as, for example, theStudio Color automated wash luminaire available from High End Systems,Inc. of Austin, Tex., and described in the aforementioned High EndSystems Product Line 1996 brochure. The computer 640 is capable ofgathering service information from preferably all of the light fixtures620, 622, 624, 626, 628, 630 and 632, and is capable of controllingparameters of preferably the light fixtures 628, 630 and 632. Ifdesired, the computer 640 may be made capable of controlling at leastsome of the parameters of the light fixtures 620, 622, 624 and 626, andmay additionally be made capable of controlling any parameters notcontrolled by the advanced controller 610. The computer 640 supportsbi-directional communications, as shown by an arrow adjacentcommunications cable 642, and the multi-parameter light fixtures 620,622, 624, 626, 628, 630 and 632 have suitable communications cableinterfaces of a type well known in the art.

Multi-parameter light fixtures 620, 622, 624 and 626 are connected toboth of the communications systems, either one of which may affect lightfixture parameters and operations such as homing and enabling ordisabling operational modes. In this event, the multi-parameter lightfixture selects which one of the communications systems to respond tousing any suitable priority system.

The selection of which light fixture connected to both the first andsecond communications systems should act as a gateway to the secondcommunications system preferably is accomplished by intelligentarbitration, by which multi-parameter light fixtures arranged ingroups—for example, one group (light fixtures 620, 622, 624 and 626)receiving communications from the first and second communications systemand another group (light fixtures 628, 630 and 632) receivingcommunications only from the second communications system—automaticallydecide amongst themselves which light fixture of the group receivingcommunications from the first and second communications system is to actas a gateway to the light fixtures of the group receiving communicationsonly from the second communications system. Methods of intelligentarbitration are well known.

In FIG. 7, the multi-parameter light fixtures 620, 622, 624, 626, 628,630 and 632 are all connected to the second communications system. Thelight fixtures are set with an operating address. Light fixtures 620,622, 624 and 626 are connected and capable of receiving communicationsover the first communications system. All light fixtures are free tocommunicate over the second communications system, although normallyoperational commands are communicated from the controller 610 to thelight fixtures 620, 622, 624 and 626 on the first communications system.Upon system power up, the multi-parameter light fixtures 620, 622, 624and 626 on the first communications system communicate amongstthemselves on a peer-to-peer basis preferably using a set of rules toavoid collisions during communications. A suitable set of rules is theCSMA/CD (Carrier Sense Multiple Access/Collision Detection) protocol.CSMA/CD is a set of rules determining how network devices respond whentwo devices attempt to use a data channel simultaneously, which iscalled a collision. CSMA/CD is well known and commonly used in standardEthernet networks. The IEEE 802.11 standard specifies a carrier sensemultiple access with collision avoidance (CSMA/CA) protocol. In thisprotocol, when a node receives a packet to be transmitted, it firstlistens to ensure no other node is transmitting. If the channel isclear, it then transmits the packet. Otherwise, it chooses a random“backoff factor” which determines the amount of time the node must waituntil it is allowed to transmit its packet. During periods in which thechannel is clear, the transmitting node decrements its backoff counter.When the channel is busy it does not decrement its backoff counter. Whenthe backoff counter reaches zero, the node transmits the packet. Sincethe probability that two nodes will choose the same backoff factor issmall, collisions between packets are minimized. This standard enablesdevices to detect a collision. The multi-parameter light fixtures 620,622, 624 and 626 establish a hierarchy amongst themselves in anysuitable way, such as, for example, by using the operating addresses orthe manufacturing addresses assigned to them.

If the first communications system is not capable of bi-directionalcommunications, as is the case with the present DMX512 protocol, or asan alternative, a hierarchy may be established using the secondcommunications system if it is bi-directional. In this event, themulti-parameter light fixtures 620, 622, 624, 626, 628, 630 and 632communicate using peer-to-peer communications over the secondcommunications system. By communicating amongst themselves on the secondcommunications system, the light fixtures 620, 622, 624, 626, 628, 630and 632 determine which amongst them both has the highest manufacturingaddress (or, alternatively, operating address) and also receives validcommunications from the first communications system. The light fixturehaving the highest manufacturing address (alternatively, the lowest orany other numeric ranking would also be suitable) and receiving validcommunications through the first communications system, for example, isselected to automatically retransmit the required operating command setfrom the first communications system to multi-parameter light fixtures620, 622, 624, 626, 628, 630 and 632 on the second communicationssystem. Light fixtures 628, 630 and 632 which are not on the firstcommunications system are thereby able to receive the command set on thefirst communications system through the multi-parameter light fixtureselected as the gateway.

The presence of two (or more) separately controlled communicationssystems permits command sets to be communicated on one while the secondcommunications system is used for additional functions such astransmitting service information, running diagnostics, transmittingoperating temperatures, updating operating code, perform manufacturerquality control, and so forth. In this manner, data traffic on the firstcommunications system is reduced and the load shared by the secondcommunications system.

The presence of two or more separately controlled communications systemsalso provides redundancy, which may be used to increase reliability. Forexample, if the light fixtures 620, 622, 624, 626, 628, 630 and 632 areall working on an automatic priority system and light fixtures 620, 622,624 and 626 are not receiving information from the advanced controller610 over the first communications system, they may operate from commandsprovided by the computer 640 over the second communications system.

The presence of two or more separately controlled communications systemsalso enables lighting systems to be adapted to a number of specialcircumstances. A lighting system in which the first communicationssystem is DMX-based and the second communications system is power linebi-directional is particularly useful, for example, for reducing laborrequired to position light fixtures in hard to reach locations. Thehigher reliability system is the hardwired DMX system, as power linesystems are still subject to interference. However, the power linesystem is capable of bi-directional communications, and is useful forreporting service conditions of the light fixtures and for handlingarbitration using CSMA/CD if CEBus is used as the power line protocol.In one illustrative arrangement, all of the light fixtures are on thepower line system while only some of the light fixtures are on the DMXsystem. The DMX system carries commands to operate all of the lightfixtures in the lighting system, so that the light fixtures on the DMXsystem receive their commands directly while light fixtures on the powerline system receive their commands through one of the light fixtures onthe DMX system acting as a gateway to the power line system. Allfixtures are responsive to the power line system for serviceinformation, since they are all connected to the power line. The secondcommunications system may instead be an RF or infrared system, ifdesired.

As a second example, a lighting system in which thirst communicationssystem uses a bi-directional protocol that is a successor to the DMXprotocol and the second communications system uses the DMX protocol isparticularly useful, for example, for facilitating a smooth transitionfrom the old DMX protocol to its successor. A multi-parameter lightfixture on the communications system using the successor protocol actsas a gateway to older lights on the communications system using theolder protocol, and both new and old controllers would be supported. Thepresent DMX protocol specifies three wires: (1) data plus; (2) datanegative; and (3) ground. Receivers are receivers only and transmittersare transmitters only. It is likely that a new standard protocol toreplace DMX will be conceived in the future that will allowbi-directional communications over the same set of wires or even acoaxial cable. The present DMX standard does specify the addition of twomore wires, a data plus and data negative, to achieve bi-directionalfull duplex, but the 5-wire full duplex system has not been readilyaccepted and is not in widespread use.

As a third example, a lighting system in which the first communicationssystem uses a bi-directional protocol for video projection lights, suchas, for example, the Ethernet protocol or a new high speedbi-directional protocol, and the second communications system uses theDMX protocol or its successor is particularly useful, for example, toenable the use of both advanced video projection light fixtures and thesimpler and older light fixtures. The fast Ethernet or new protocol maycontain information for the simpler and older light fixtures, and anadvanced video projection light fixtures may act as a gateway to sendDMX protocol commands to the light fixtures on the DMX system.

It will be appreciated that the lighting systems of the second and thirdexamples may be provided with a third communications system that usesthe power line protocol to make installation more convenient or forother reasons.

The digital circuits of three two-channel multi-parameter light fixturesare shown in FIG. 8 through FIG. 10; it will be appreciated that morethan two channels to support more than two communications systems may beprovided if desired. As these types of circuits are generally well knownin the art, they have been simplified for clarity to show thearrangement of communications system interfaces relative to themicroprocessor and the device terminals. Suitable circuits are availablefrom various manufacturers, including National Semiconductor, Inc. ofSanta Clara, Calif., and Intellon Corporation of Ocala, Fla.

FIG. 8 shows an arrangement suitable for a multi-parameter light systemhaving two cable communications systems. The microprocessor sub-system710 interfaces to the first cable communications system through a cableinterface circuit 702, and interfaces to the second cable communicationssystem through a cable interface circuit 704. A power supply 712 is alsoshown.

FIG. 9 shows an arrangement suitable for a multi-parameter light systemhaving one cable communications systems routed to only some of themulti-parameter light fixtures but requiring communications to all ofthe multi-parameter light fixtures. The second communications system isimplemented through the power line. The microprocessor sub-system 710interfaces to the first cable communications system through the cableinterface circuit 702, and interfaces to a power line to the powersupply 712 through a power line interface circuit 802.

FIG. 10 shows an arrangement suitable for a multi-parameter light systemhaving one cable communications systems routed to only some of themulti-parameter light fixtures but requiring communications to all ofthe multi-parameter light fixtures. The second communications system isimplemented wirelessly through, for example, radio frequencycommunications. The microprocessor sub-system 710 interfaces to thefirst cable communications system through the cable interface circuit702, and interfaces to a radio frequency transceiver 902, which isconnected to an antenna 900, through a transceiver interface 904.

While the terminals in FIGS. 8 through 10 are shown as single ended forclarity, it will be appreciated that the terminals are representative ofthe numerous terminal arrangements well known in the art, includingunidirectional and bi-directional ports as well as various arrangementsof connectors including looped through connectors and connectors thatincorporate line amplifiers and pulse shapers. For example, FIG. 11shows a simple loop-through connector in which one terminal isdesignated COM IN and the other is designated COM OUT, FIG. 12 shows abi-directional directional terminal designated COM IN/OUT, FIG. 13 showsa separate COM IN and COM OUT terminals with respective linedrivers/pulse shapers 1202 and 1204, and FIG. 14 shows a bi-directionalterminal designated COM IN/OUT connected to an input line driver/pulseshaper 1302 and an output line driver/pulse shaper 1304.

The description of the invention and its applications as set forthherein is illustrative and is not intended to limit the scope of theinvention as set forth in the following claims. Variations andmodifications of the embodiments disclosed herein are possible, andpractical alternatives to and equivalents of the various elements of theembodiments are known to those of ordinary skill in the art. These andother variations and modifications of the embodiments disclosed hereinmay be made without departing from the scope and spirit of the inventionas set forth in the following claims.

What is claimed is:
 1. A multi-parameter light fixture comprising: ahousing; a lamp assembly contained in the housing; a first digitalcommunications node contained in the housing and having a first controloutput coupled to the lamp assembly and a first communications port; asecond digital communications node contained in the housing and having asecond communications port; and a gateway circuit contained in thehousing and coupled between the first digital communications node andthe second digital communications node.
 2. A multi-parameter lightfixture as in claim 1, wherein at least one of the first and secondcommunications nodes supports bi-directional digital communications. 3.A multi-parameter light fixture as in claim 1, wherein the seconddigital communications node further comprises a second control outputcoupled to the lamp assembly.
 4. A multi-parameter light fixture as inclaim 3 wherein both the first and second digital communications nodescomprise a “lamp on” parameter.
 5. A multi-parameter light fixture as inclaim 3 wherein: the lamp assembly comprises a plurality of controllablecomponents; and the first control output controls a first group of thecontrollable components and the second control output controls a secondgroup of the controllable components, the first and second groups of thecontrollable components having at least one controllable component incommon.
 6. A multi-parameter light fixture as in claim 1, wherein thefirst and second digital communications nodes are compliant withdifferent communications protocols.
 7. A multi-parameter light fixtureas in claim 1 wherein the first digital communications node comprises a“lamp on” parameter.
 8. A multi-parameter light fixture as in claim 1wherein the housing comprises an electronics module and a light housingmoveably coupled thereto, the first and second communications nodes andthe gateway circuit being contained in the electronics module and thelamp assembly being contained in the light housing.
 9. A multi-parameterlight fixture as in claim 1 wherein the housing comprises a unitarylight housing, the first and second communications nodes, the gatewaycircuit, and the lamp assembly being contained in the unitary lighthousing.
 10. A multi-parameter light fixture comprising: a housing; alamp assembly contained in the housing; a first digital-communicationsnode contained in the housing and having a first control output coupledto the lamp assembly and a first communications port; and a seconddigital communications node contained in the housing and having a secondcommunications port; wherein at least one of the first and seconddigital communications nodes supports bi-directional digitalcommunications.
 11. A multi-parameter light fixture as in claim 10,wherein at least one of the first and second digital communicationsnodes supports DMX protocol digital communications.
 12. Amulti-parameter light fixture as in claim 10, wherein the second digitalcommunications node further comprises a second control output coupled tothe lamp assembly.
 13. A multi-parameter light fixture as in claim 12wherein both the first and second digital communications nodes comprisea “lamp on” parameter.
 14. A multi-parameter light fixture as in claim12, wherein: the lamp assembly comprises a plurality of controllablecomponents; and the first control output controls a first group of thecontrollable components and the second control output controls a secondgroup of the controllable components, the first and second groups of thecontrollable components having at least one controllable component incommon.
 15. A multi-parameter light fixture as in claim 10, wherein thefirst and second digital communications nodes are compliant withdifferent communications protocols.
 16. A multi-parameter light fixtureas in claim 10 wherein the first digital communications node comprises a“lamp on” parameter.
 17. A multi-parameter light fixture as in claim 10wherein the housing comprises an electronics module and a light housingmoveably coupled thereto, the first and second communications nodesbeing contained in the electronics module and the lamp assembly beingcontained in the light housing.
 18. A multi-parameter light fixture asin claim 10 wherein the housing comprises a unitary light housing, thefirst and second communications nodes and the lamp assembly beingcontained in the unitary light housing.